A hot plate of an electric oven connected to a 220V line, has two resistance coils A and B , each of 24 Omega resistance, which may be used separately, in series, or in parallel. What are the currents in the three cases?

A hot plate of an electric oven connected to a 220V line, has two resi

1.	A hot plate of an electric oven connected to a 220V line, has two resistance coils A and B , each of 24 Omega resistance, which may be used separately, in series, or in parallel. What are the currents in the three cases?
Answer» Solution :It is given that potential difference `V=220V` resistance of coil A `(R_A)` = Resistance of coil B `(R_B)=24 Omega` (i) When EITHER coil A or B is used SEPARATELY, the current `I=V/R_A=V/R_B=(220V)/(24 Omega)=9.2 A` (ii) When the two coils are used in series, total resistance `R_s=R_A+R_B=24+24=48 Omega` `therefore` Current flowing `I=V/R_s=(220V)/(48 Omega)=4.6 A` (iii) When the two coils are used in parallel , total resistance `R_p` is given by `1/R_p-1/R_A+1/R_B=1/24+1/24=2/24=1/12 implies R_p=12 Omega` `therefore` Current flowing `I=V/R_p=(220V)/(12 Omega)=18.3 A`